Precoding matrix indicator determination in wireless communication systems

ABSTRACT

The described technology is generally directed towards reducing the complexity for finding the precoding matrix index/rank information channel state information in New Radio wireless systems. Described is using the beam characteristics of X1 (wideband component index) and X2 (subband component index) such that a user equipment first determines a best chosen X2 for only one X1 index. Thereafter, the user equipment uses the chosen index of X2 for the other X1 indices, thereby reducing the complexity of the precoding matrix index/rank information search by reducing the search space in the codebook, which reduces the number of computations at the user equipment side without significantly impacting the performance.

TECHNICAL FIELD

The subject application is related to wireless communication systems,and, for example, to determining the precoding matrix indicator (PMI) inmultiple antenna wireless communication systems.

BACKGROUND

In wireless communication systems, multiple input multiple output(MIMO), is an antenna technique configured to improve the spectralefficiency and thereby boost overall system capacity. The MIMO techniqueuses a commonly known notation (M×N) to represent MIMO configuration interms number of transmit (M) and receive antennas (N) on one end of thetransmission system. MIMO systems can significantly increase the datacarrying capacity of wireless systems. MIMO can be used for achievingdiversity gain, spatial multiplexing gain and beamforming gain.

In new radio (NR), sometimes referred to as 5G, a user equipmentcomputes channel estimates based on known pilots or reference signalsfrom the 5G system, computes the parameters needed for channel stateinformation (CSI) reporting and conveys this information to the networkthrough the feedback channel. More particularly, the user equipmentreceiver estimates channel quality (typicallysignal-to-interference-plus-noise ratio, or SINR) from channel sounding,and computes a preferred precoding matrix indicator (PMI), rankindicator (RI), and Channel Quality Indicator (CQI) for the nextdownlink transmission.

For downlink data transmission, the demodulation reference signals(DM-RS) and the data are multiplied by the precoding matrix selected bythe network device (e.g., gNode B) and transmitted. The user equipmentreceiver estimates the effective channel (the channel multiplied by theprecoding matrix) and demodulates the data.

Codebook based precoding allows the receiver to explicitly identify theprecoding matrix/vector that is to be used for transmission, based on acodebook. As an example, in the 3GPP NR standard, separate codebooks aredefined for various combinations of the number of transmit antennas andthe number of transmission layers; (the number of transmission layers isalso referred to as rank information (RI)).

Finding the PMI/RI with larger numbers of antennas is a highly complexproblem, involving many computations, and is based on an exhaustivesearch over codebook elements; the codebook size grows as the number ofantennas increases. For example with four CSI-RS ports, the userequipment needs to search eighty precoding entities to find the rankinformation and precoding index. This can drain the user equipmentbattery life, increase power consumption, and/or consume significantmemory and processing units at the user equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The technology described herein is illustrated by way of example and notlimited in the accompanying figures in which like reference numeralsindicate similar elements and in which:

FIG. 1 illustrates an example wireless communication system in which anetwork node device (e.g., network node) and user equipment (UE) canimplement various aspects and implementations of the subject disclosure.

FIGS. 2 and 3 is a flow diagram representing example operations fordetermining a precoding matrix indicator without performing a fullsearch, in accordance with various aspects and implementations of thesubject disclosure.

FIGS. 4-6 are graphical representations of horizontal radiation patternsdifferent wideband-based component (X1) and suband-based component (X2)index values, in accordance with various aspects and implementations ofthe subject disclosure.

FIGS. 7-9 are graphical representations of rank 1 precoding matrixindicators at different signal-to-noise ratio values, in accordance withvarious aspects and implementations of the subject disclosure.

FIG. 10 is a graphical representation of spectral efficiency versussignal-to-noise ratios with full search for PMI reporting versus reducedsearch based on the technology described herein, in accordance withvarious aspects and implementations of the subject disclosure.

FIG. 11 illustrates a flow diagram of example user equipment operationsfor determining a precoding matrix indicator without performing a fullsearch, in accordance with various aspects and implementations of thesubject disclosure.

FIG. 12 illustrates a flow diagram of example user equipment operations,comprising operations for determining and reporting a precoding matrixindicator without performing a full search, in accordance with variousaspects and implementations of the subject disclosure.

FIGS. 13 and 14 illustrate a flow diagram of example user equipmentoperations for determining a precoding matrix indicator withoutperforming a full search, in accordance with various aspects andimplementations of the subject disclosure.

FIG. 15 illustrates an example block diagram of an example mobilehandset operable to engage in a system architecture that facilitateswireless communications according to one or more embodiments describedherein.

FIG. 16 illustrates an example block diagram of an example computeroperable to engage in a system architecture that facilitates wirelesscommunications according to one or more embodiments described herein.

DETAILED DESCRIPTION

Briefly, one or more aspects of the technology described herein aregenerally directed towards reducing the complexity in determining theCSI (e.g., including the rank information and precoding index) for bothperiodic and aperiodic reporting. In one or more implementations, thebeam characteristics of the wideband and subband component indices (X1and X2) are used by a user equipment process that selects only one X1,and for that X1, chooses the X2 that provides the “best” link qualitymetric (corresponding to capacity or mutual information). The userequipment process then uses the chosen index of X2 for the other X1indices to find the “best” [X1, chosen X2] combination, and need not useany other X2 indices. This significantly reduces the complexity of theRI/PMI search, because the search space in the codebook is reduced,thereby reducing the number of computations at the user equipment.Evaluations demonstrate that the user equipment process significantlyreduces the complexity but does not significantly impact theperformance.

Thus, one or more aspects of the technology described herein comprisehaving the user equipment (MIMO receiver) estimate the channel fromknown pilots or reference signals (and/or data), and compute thepost-processing SINR for one value of X1, e.g., X1=1, and for the valuesof X2 that correspond to that X1. The user equipment computes a firstgroup of hypotheses comprising the link quality metric (mutualinformation or capacity) from the computed SINR for the [X1=1, X2]combinations, and chooses the X2 of these hypotheses that maximizes themutual information or capacity.

Once the X2 is chosen, the user equipment computes the link qualitymetric for the other X1 values in conjunction with the chosen X2 value,to obtain a second group of hypotheses, comprising [X1, chosen X2]combinations. The user equipment selects the PMI based on the secondgroup of hypotheses, that is, the combination that maximizes the mutualinformation or capacity. The user equipment reports the computed PMIparameters to the network device.

It should be understood that any of the examples and terms used hereinare non-limiting. For instance, the examples are based on New Radio (NR,sometimes referred to as 5G) communications between a user equipmentexemplified as a smartphone or the like and network device; howevervirtually any communications devices may benefit from the technologydescribed herein, and/or their use in different spectrums may likewisebenefit. Thus, any of the embodiments, aspects, concepts, structures,functionalities or examples described herein are non-limiting, and thetechnology may be used in various ways that provide benefits andadvantages in radio communications in general.

In some embodiments the non-limiting term “radio network node” or simply“network node,” “radio network device or simply “network device” is usedherein. These terms may be used interchangeably, and refer to any typeof network node that serves user equipment and/or connected to othernetwork node or network element or any radio node from where userequipment receives signal. Examples of radio network nodes are Node B,base station (BS), multi-standard radio (MSR) node such as MSR BS,gNodeB, eNode B, network controller, radio network controller (RNC),base station controller (BSC), relay, donor node controlling relay, basetransceiver station (BTS), access point (AP), transmission points,transmission nodes, RRU, RRH, nodes in distributed antenna system (DAS)etc.

In some embodiments the non-limiting term user equipment (UE) is used.It refers to any type of wireless device that communicates with a radionetwork node in a cellular or mobile communication system. Examples ofuser equipment are target device, device to device (D2D) user equipment,machine type user equipment or user equipment capable of machine tomachine (M2M) communication, PDA, Tablet, mobile terminals, smart phone,laptop embedded equipped (LEE), laptop mounted equipment (LME), USBdongles etc.

FIG. 1 illustrates an example wireless communication system 100 inaccordance with various aspects and embodiments of the subjecttechnology. In one or more embodiments, the system 100 can comprise oneor more user equipment UEs 102(1)-102(n).

In various embodiments, the system 100 is or comprises a wirelesscommunication network serviced by one or more wireless communicationnetwork providers. In example embodiments, a UE 102 can becommunicatively coupled to the wireless communication network via anetwork device 104 (e.g., network node). The network device 104 cancommunicate with the user equipment (UE) 102, thus providingconnectivity between the UE and the wider cellular network.

In example implementations, each UE 102 such as the UE 102(1) is able tosend and/or receive communication data via a wireless link to thenetwork device 104. The dashed arrow lines from the network device 104to the UE 102 represent downlink (DL) communications and the solid arrowlines from the UE 102 to the network devices 104 represents uplink (UL)communications.

The system 100 can further include one or more communication serviceprovider networks 106 that facilitate providing wireless communicationservices to various user equipment, including UEs 102(1)-102(n), via thenetwork device 104 and/or various additional network devices (not shown)included in the one or more communication service provider networks 106.The one or more communication service provider networks 106 can includevarious types of disparate networks, including but not limited to:cellular networks, femto networks, picocell networks, microcellnetworks, internet protocol (IP) networks Wi-Fi service networks,broadband service network, enterprise networks, cloud based networks,and the like. For example, in at least one implementation, system 100can be or include a large scale wireless communication network thatspans various geographic areas. According to this implementation, theone or more communication service provider networks 106 can be orinclude the wireless communication network and/or various additionaldevices and components of the wireless communication network (e.g.,additional network devices and cell, additional UEs, network serverdevices, etc.).

The network device 104 can be connected to the one or more communicationservice provider networks 106 via one or more backhaul links 108. Forexample, the one or more backhaul links 108 can comprise wired linkcomponents, such as a T1/E1 phone line, a digital subscriber line (DSL)(e.g., either synchronous or asynchronous), an asymmetric DSL (ADSL), anoptical fiber backbone, a coaxial cable, and the like. The one or morebackhaul links 108 can also include wireless link components, such asbut not limited to, line-of-sight (LOS) or non-LOS links which caninclude terrestrial air-interfaces or deep space links (e.g., satellitecommunication links for navigation).

Some embodiments are described in particular for 5G new radio systems.The embodiments are however applicable to any radio access technology(RAT) or multi-RAT system where the user equipment operates usingmultiple carriers e.g. LTE FDD/TDD, WCMDA/HSPA, GSM/GERAN, Wi Fi, WLAN,WiMax, CDMA2000 etc.

The embodiments are applicable to single carrier as well as tomulticarrier (MC) or carrier aggregation (CA) operation of the userequipment. The term carrier aggregation (CA) is also called (e.g.interchangeably called) “multi-carrier system”, “multi-cell operation”,“multi-carrier operation”, “multi-carrier” transmission and/orreception.

Note that the solutions outlined equally applies for Multi RAB (radiobearers) on some carriers (that is data plus speech is simultaneouslyscheduled). Some embodiments are described in particular for 5G newradio systems. The embodiments are however applicable to any radioaccess technology (RAT) or multi-RAT system where the user equipmentoperates using multiple carriers e.g. LTE FDD/TDD, WCMDA/HSPA,GSM/GERAN, Wi Fi, WLAN, WiMax, CDMA2000 etc.

The embodiments are applicable to single carrier as well as tomulticarrier (MC) or carrier aggregation (CA) operation of the userequipment. The term carrier aggregation (CA) is also called (e.g.interchangeably called) “multi-carrier system”, “multi-cell operation”,“multi-carrier operation”, “multi-carrier” transmission and/orreception.

Note that the solutions outlined equally applies for Multi RAB (radiobearers) on some carriers (that is, data plus speech is simultaneouslyscheduled).

FIG. 1 illustrates an example wireless communication system 100 inaccordance with various aspects and embodiments of the subjecttechnology. In one or more embodiments, the system 100 can comprise oneor more user equipment UEs 102(1)-102(n).

In various embodiments, the system 100 is or comprises a wirelesscommunication network serviced by one or more wireless communicationnetwork providers. In example embodiments, a UE 102 can becommunicatively coupled to the wireless communication network via anetwork device 104 (e.g., network node). The network device 104 cancommunicate with the user equipment (UE) 102, thus providingconnectivity between the UE and the wider cellular network.

In example implementations, each UE 102 such as the UE 102(1) is able tosend and/or receive communication data via a wireless link to thenetwork device 104. The dashed arrow lines from the network device 104to the UE 102 represent downlink (DL) communications and the solid arrowlines from the UE 102 to the network devices 104 represents uplink (UL)communications.

The system 100 can further include one or more communication serviceprovider networks 106 that facilitate providing wireless communicationservices to various user equipment, including UEs 102(1)-102(n), via thenetwork device 104 and/or various additional network devices (not shown)included in the one or more communication service provider networks 106.The one or more communication service provider networks 106 can includevarious types of disparate networks, including but not limited to:cellular networks, femto networks, picocell networks, microcellnetworks, internet protocol (IP) networks Wi-Fi service networks,broadband service network, enterprise networks, cloud based networks,and the like. For example, in at least one implementation, system 100can be or include a large scale wireless communication network thatspans various geographic areas. According to this implementation, theone or more communication service provider networks 106 can be orinclude the wireless communication network and/or various additionaldevices and components of the wireless communication network (e.g.,additional network devices and cell, additional UEs, network serverdevices, etc.).

The network device 104 can be connected to the one or more communicationservice provider networks 106 via one or more backhaul links 108. Forexample, the one or more backhaul links 108 can comprise wired linkcomponents, such as a T1/E1 phone line, a digital subscriber line (DSL)(e.g., either synchronous or asynchronous), an asymmetric DSL (ADSL), anoptical fiber backbone, a coaxial cable, and the like. The one or morebackhaul links 108 can also include wireless link components, such asbut not limited to, line-of-sight (LOS) or non-LOS links which caninclude terrestrial air-interfaces or deep space links (e.g., satellitecommunication links for navigation).

The wireless communication system 100 can employ various cellularsystems, technologies, and modulation schemes to facilitate wirelessradio communications between devices (e.g., the UE 102 and the networkdevice 104). While example embodiments might be described for 5G newradio (NR) systems, the embodiments can be applicable to any radioaccess technology (RAT) or multi-RAT system where the UE operates usingmultiple carriers e.g. LTE FDD/TDD, GSM/GERAN, CDMA2000 etc. Forexample, the system 100 can operate in accordance with global system formobile communications (GSM), universal mobile telecommunications service(UMTS), long term evolution (LTE), LTE frequency division duplexing (LTEFDD, LTE time division duplexing (TDD), high speed packet access (HSPA),code division multiple access (CDMA), wideband CDMA (WCMDA), CDMA2000,time division multiple access (TDMA), frequency division multiple access(FDMA), multi-carrier code division multiple access (MC-CDMA),single-carrier code division multiple access (SC-CDMA), single-carrierFDMA (SC-FDMA), orthogonal frequency division multiplexing (OFDM),discrete Fourier transform spread OFDM (DFT-spread OFDM) single carrierFDMA (SC-FDMA), Filter bank based multi-carrier (FBMC), zero tailDFT-spread-OFDM (ZT DFT-s-OFDM), generalized frequency divisionmultiplexing (GFDM), fixed mobile convergence (FMC), universal fixedmobile convergence (UFMC), unique word OFDM (UW-OFDM), unique wordDFT-spread OFDM (UW DFT-Spread-OFDM), cyclic prefix OFDM CP-OFDM,resource-block-filtered OFDM, Wi Fi, WLAN, WiMax, and the like. However,various features and functionalities of system 100 are particularlydescribed wherein the devices (e.g., the UEs 102 and the network device104) of system 100 are configured to communicate wireless signals usingone or more multi carrier modulation schemes, wherein data symbols canbe transmitted simultaneously over multiple frequency subcarriers (e.g.,OFDM, CP-OFDM, DFT-spread OFMD, UFMC, FMBC, etc.). The embodiments areapplicable to single carrier as well as to multicarrier (MC) or carrieraggregation (CA) operation of the UE. The term carrier aggregation (CA)is also called (e.g. interchangeably called) “multi-carrier system”,“multi-cell operation”, “multi-carrier operation”, “multi-carrier”transmission and/or reception. Note that some embodiments are alsoapplicable for Multi RAB (radio bearers) on some carriers (that is dataplus speech is simultaneously scheduled).

In various embodiments, the system 100 can be configured to provide andemploy 5G wireless networking features and functionalities. With 5Gnetworks that may use waveforms that split the bandwidth into severalsub bands, different types of services can be accommodated in differentsub bands with the most suitable waveform and numerology, leading toimproved spectrum utilization for 5G networks. Notwithstanding, in themmWave spectrum, the millimeter waves have shorter wavelengths relativeto other communications waves, whereby mmWave signals can experiencesevere path loss, penetration loss, and fading. However, the shorterwavelength at mmWave frequencies also allows more antennas to be packedin the same physical dimension, which allows for large-scale spatialmultiplexing and highly directional beamforming.

Performance can be improved if both the transmitter and the receiver areequipped with multiple antennas. Multi-antenna techniques cansignificantly increase the data rates and reliability of a wirelesscommunication system. The use of multiple input multiple output (MIMO)techniques, which was introduced in the third-generation partnershipproject (3GPP) and has been in use (including with LTE), is amulti-antenna technique that can improve the spectral efficiency oftransmissions, thereby significantly boosting the overall data carryingcapacity of wireless systems. The use of multiple-input multiple-output(MIMO) techniques can improve mmWave communications; MIMO can be usedfor achieving diversity gain, spatial multiplexing gain and beamforminggain.

Note that using multi-antennas does not always mean that MIMO is beingused. For example, a configuration can have two downlink antennas, andthese two antennas can be used in various ways. In addition to using theantennas in a 2×2 MIMO scheme, the two antennas can also be used in adiversity configuration rather than MIMO configuration. Even withmultiple antennas, a particular scheme might only use one of theantennas (e.g., LTE specification's transmission mode 1, which uses asingle transmission antenna and a single receive antenna). Or, only oneantenna can be used, with various different multiplexing, precodingmethods etc.

The MIMO technique uses a commonly known notation (M×N) to representMIMO configuration in terms number of transmit (M) and receive antennas(N) on one end of the transmission system. The common MIMOconfigurations used for various technologies are: (2×1), (1×2), (2×2),(4×2), (8×2) and (2×4), (4×4), (8×4). The configurations represented by(2×1) and (1×2) are special cases of MIMO known as transmit diversity(or spatial diversity) and receive diversity. In addition to transmitdiversity (or spatial diversity) and receive diversity, other techniquessuch as spatial multiplexing (comprising both open-loop andclosed-loop), beamforming, and codebook-based precoding can also be usedto address issues such as efficiency, interference, and range.

In FIG. 1, as described herein, a user equipment (e.g., 102(1)) isconfigured to receive references signals and data 110, and use those toestimate the PMI (and RI) via a PMI and RI estimation process 112. Acodebook 114 may be searched for the (note that as used herein, PMI canbe defined as an index within the 114, or the PMI can be defined as aprecoder itself, depending on the context). Once the PMI and RI areestimated, these data are returned as part of a CSI report 116 to thenetwork device 104. Described herein is how the user equipment estimatesa suitable CSI, e.g., CQI/PMI/RI, in order to attempt to maximize thethroughput and simultaneously maintain the block-error-rate (BLER)constraint.

The following table, TABLE 1, represents an example CSI report:

PMI- PMI-FormatIndicator = FormatIndicator = subbandPMI or CQI-widebandPMI and CQI- FormatIndicator = subbandCQI FormatIndicator = CSIPart II widebandCQI CSI Part I wideband Sideband CRI CRI Wideband CQISubband for the second differential TB CQI for the second TB of all evensubbands Rank Indicator Rank PMI wideband PMI Indicator (X1 and X2)subband information fields X₂ of all even subbands Layer Indicator Layer— Subband Indicator differential CQI for the second TB of all oddsubbands PMI wideband Wideband — PMI (X1 and X2) CQI subband informationfields X₂ of all odd subbands Wideband CQI Subband — — differential CQIfor the first TB

As described herein, in NR, the user equipment needs to estimate asuitable CSI, including, CQI/PMI/RI, in order to maximize the throughputwhile simultaneously maintaining the block-error-rate (BLER) constraint,which can be mathematically described by a joint (integer) optimizationproblem,

$\begin{matrix}\begin{matrix}\max\limits_{{CQI},{PMI},{RI}} & {{Throughput}\mspace{11mu}\left( {{CQI},{PMI},{RI}} \right)} \\{{subject}\mspace{14mu}{to}} & {{BLER} \leq {Threshold}}\end{matrix} & (1)\end{matrix}$

This joint (discrete/integer) optimization problem does not have anyclosed-form solution. Hence, one technique tries to estimate a suitablePMI/RI (independent of CQI); thereafter, a suitable CQI is estimatedaccordingly for the chosen PMI (and RI).

By way of example, consider a single-cell scenario having perfect timeand synchronization, a received system model for (closed-loop) SM persub-carrier (post-FFT) can be shown as,Y=HWX+N  (2)where, Y∈X^(N) ^(r) ^(×1) corresponds to a received signal vector, andH∈X^(N) ^(r) ^(×N) ^(t) describes an overall channel matrix. A complexzero-mean Gaussian noise vector n∈C^(N) ^(r) ^(×1) has covariance R_(n).An unknown complex data/symbol vector is denoted by x∈A^(N) ^(L) ^(×1)(having normalized power E{xx^(H)}=R_(x)=I) corresponding to M-QAM(e.g., 64-QAM) constellation A. A (complex) precoder W_(PMI)∈Π^(N) ^(t)^(×N) ^(L) is selected from a given/known codebook Π having N_(Π) numberof precoders (where, PMI={0, 1, . . . N_(Π)-1}) for a givenrank≤min{N_(r), N_(t)}.

The post-processing SINR per i^(th) spatial layer for a given PMI,assuming linear-MMSE detector employed at the receiver, reads

$\begin{matrix}{{{SINR}_{i} = {\frac{1}{\left\lbrack {{W_{PMI}^{H}H^{H}R_{n}^{- 1}{HW}_{PMI}} + I_{N_{L}}} \right\rbrack_{i,i}} - 1}},} & (3)\end{matrix}$where [A]_(i,i) corresponds to an i^(th) diagonal element of a matrix A.

In order to estimate a suitable PMI/RI, a link-quality metric (LQM),e.g., mean mutual information, denoted as mMI (per sub-band/wide-band)is computed, as given below,

$\begin{matrix}{{{mMI}\left( {{PMI},{RI}} \right)} = {\left( \frac{1}{K \cdot {rank}} \right){\sum\limits_{k = 1}^{K}{\sum\limits_{i = 1}^{{RI} = {rank}}{I\left( {{SINR}_{i}\lbrack k\rbrack} \right)}}}}} & (4)\end{matrix}$where, I (SINR_(i)[k]) is a mutual information that is a function ofpost-processing SINR_(i)[k] (and modulation alphabet A) as given inTable 6 for i^(th) spatial layer and k^(th) resource-element. The numberof resource-elements employed for the computation of the aforementionedLQM is given by a parameter K (depending on the wide-band/sub-band PMIestimate).

TABLE 2 Mutual information for 4-QAM, 16-QAM and 64-QAM. ModulationAlphabet A Mutual Information per symbol  4-QAM I (SINR_(i)) ≈ J({squareroot over (4 SINR_(i))}) 16-QAM I (SINR_(i)) ≈ (½)J(0.8818{square rootover (SINR_(i))}) + (¼)J(1.6764{square root over (SINR_(i))}) +(¼)J(0.9316 {square root over (SINR_(i))}) 64-QAM I (SINR_(i)) ≈(⅓)J(1.1233{square root over (SINR_(i))}) + (⅓)J(0.4381{square root over(SINR_(i))}) + (⅓)J(0.4765 {square root over (SINR_(i))})${J(a)} \approx \left\{ {\begin{matrix}\begin{matrix}{{{- 0.04210610}\mspace{14mu} a^{3}} + {0.209252\mspace{14mu} a^{2}}} \\{{{- 0.00640081}\mspace{14mu} a},}\end{matrix} & {0 < a < 1.6363} \\\begin{matrix}{1 - {\exp\left( {{0.00181491\mspace{14mu} a^{3}} - {0.142675\mspace{14mu} a^{2}} -} \right.}} \\{\left. {{{- 0.08220540}\mspace{14mu} a} + 0.0549608} \right),}\end{matrix} & {1.6363 < a < \infty}\end{matrix}.} \right.$

After having the estimate of mMI (per sub-band/wide-band), the PMI andRI can be jointly estimated, employing unconstrained optimization, whichcan be given as

$\max\limits_{{PMI},{Ri}}{{{mMI}\left( {{PMI},{RI}} \right)}.}$

Note that conventionally, an exhaustive search of the PMI and RI arecomputed based on the mutual information approach. Note that the CQI iscomputed afterwards with the chosen PMI/RI.

Instead of finding mutual information, in an alternative approach, thecapacity is calculated as shown below in equation (4):

$\begin{matrix}{{{capacity}\mspace{11mu}\left( {{PMI},{RI}} \right)} = {\left( \frac{1}{K \cdot {rank}} \right){\sum\limits_{k = 1}^{K}{\sum\limits_{i = 1}^{{RI} = {rank}}{\log_{2}\left( {1 + {{SINR}_{i}\lbrack k\rbrack}} \right)}}}}} & (4)\end{matrix}$

In contrast to the conventional, exhaustive search, FIGS. 2 and 3 showexample logic of the PMI and RI estimation process 112 (FIG. 1)described herein, in the form of operations. Operation 202 representsestimating a channel from known pilots or reference signals (and/ordata), e.g., received by the user equipment from the network device 104as represented by block 110 of FIG. 1.

Operation 204 represents selecting an X1 (wideband component) index,e.g., X1=1 (although any of the available X1 indices can be selected,such as randomly. Operation 206 represents selecting an X2 (subbandcomponent) index value that corresponds to the selected X1 index value;X2 can be selected in any order/using any technique, e.g., from a firstto last index value, as long as each X2 gets selected.

Operation 208 computes the SINR for the [selected X1, currently selectedX2] combination, which is saved in a first group of results. Operations212 and 214 repeat the computations/result savings for each other X2,using the selected X1.

Once the first group of results is obtained, operation 216 chooses achosen X2 index value based on which [X1, X2] combination in the firstgroup maximizes the mutual information or capacity; this X2 is referredto herein as the chosen X2.

Once the chosen X2 is known, the operations continue at operation 302 ofFIG. 3, to find the X1 index value that works “best” with the chosen X2value. Operation 302 saves the already computed result for the mutualinformation or capacity for the [selected X1, chosen X2] in associationwith a second group. Operation 304 selects a different X1, and operation306 computes the SINR with the [different X1, chosen X2] values. Thisresult is saved in the second group.

Operation 310 repeats the process by returning to operation 304 fordifferent X1 index values, using the chosen X2, until none remain.

At this time, as represented by operation 312, one of the [X1, chosenX2] combinations maximizes the mutual information or capacity relativeto the others, e.g., determined as described herein. This combination isselected and used for the PMI estimation; as can be seen from TABLE 3,the codebook search is significantly reduced relative to the fullsearch:

TABLE 3 Comparison of conventional versus technology described herein:Number of Total Total number combinations number of of combinations % offor combinations for the savings X1 and X2 (existing full technology inthe Rank X1 X2 search) described herein search 1 8 4 32  4 + 7 = 1165.63 2 8 2 16 2 + 7 = 9 43.75 3 8 2 16 2 + 7 = 9 43.75 4 8 2 16 2 + 7 =9 43.75

As can be seen, is that for a given index X1=i, with the maximumcapacity obtained for index say X2=j, then for any index X1, the maximumcapacity is obtained for X2=j for that PMI. As an example, FIGS. 4, 5and 6 show the radiation patterns for rank equal to one, with X1=1,X1=2, and X1=3, respectively, for X2=1, 2, 3, 4. Note that rectangularantennas were used for plotting these radiation patterns.

It can be seen from FIGS. 4-6 that the radiation pattern in generaldepends on X2, and is generally the same irrespective of X1. That is,the phase angle theta of X1−X2 is generally the same for any X1. Thus,as described herein, by finding the “best” X2 index for one X1, then thesame X2 index can be used for the remaining X1.

To verify this principle, FIGS. 7-9 verify the capacity estimationduring the CSI computation for the full set of PMIs. As shown in FIG. 7,in which the capacity at SNR is equal to −5 dB, it can be observed thatfor any given group (a group is indicated by a black oval) the fourthindex typically provides the maximum capacity (and is very close for theexceptions). The same trend is observed for different SNRs as shown inFIG. 8 (SNR=5 dB) and FIG. 9 (SNR=5 dB). Thus, by finding the index ofX2 that maximizes the capacity for a given X1, then the search space forthe other X1 can be reduced.

Thus, in one or more implementations, the user equipment/receivercomputes the PMI using a complete search for only one index of X1, thatis, computes the capacity for only one X1 and each of the values of X2.Then the user equipment/receiver computes the index of X2 that gives thebest capacity. Once the chosen value of index X2 is thus obtained, sameX2 index is used for the other X1s in computing the link quality metric.In this way, the receiver node eliminates computing the link qualitymetrics of for all the other X2 indices for the remaining indices forX1.

FIG. 10 shows link simulation results performed with full search for PMIreporting and with the technology described herein. Note that to showthe benefits, the spectral efficiency is plotted with rank=1. It can beobserved that the performance of the technology described herein isequal to that of the performance of the full search.

One or more aspects, generally represented in FIG. 11, are generallydirected towards selecting, by a user equipment comprising a processor,a starting wideband-based index (X1) from indices of widebandinformation (operation 1102). Operation 1104 represents determining, bythe user equipment, signal-to-interference-plus-noise ratio values forthe starting wideband-based index and a group of indices of subbandinformation (X2) corresponding to the starting wideband-based index.Operation 1106 represents determining, by the user equipment from thesignal-to-interference-plus-noise ratio values, a first group of linkquality metric values, and operation 1108 represents choosing, by theuser equipment, a chosen subband-based index from the group of indicesof subband information based on the first group of link quality metricvalues. Operation 1110 represents determining, by the user equipment, asecond group of link quality metric values based on the indices ofwideband information and the chosen subband-based index, and operation1112 represents selecting, by the user equipment, a precoding matrixindicator based on the second group of link quality metric values, by anetwork device comprising a processor.

Selecting the precoding matrix indicator can comprise searching acodebook based on a selected wideband index and the chosen subband-basedindex. Aspects can comprise estimating, by the user equipment, achannel, wherein the obtaining the signal-to-interference-plus-noiseratio values can comprise determining thesignal-to-interference-plus-noise ratio values based on the channel.Aspects can comprise reporting, by the user equipment, parameter valuescorresponding to the precoding matrix indicator to a network device.

Determining the first group of link quality metric values based on thesignal-to-interference-plus-noise ratio values can comprise determiningmutual information values for the starting wideband-based index and thegroup of indices of subband information corresponding to the initialwideband-based index based on the signal-to-interference-plus-noiseratio values. Choosing the chosen subband-based index from the group ofindices of subband information based on the first group of link qualitymetric values can comprise selecting the subband-based index, which inconjunction with the starting wideband-based index, maximizes mutualinformation values based on the signal-to-interference-plus-noise ratiovalues.

Determining the first group of link quality metric values based on thesignal-to-interference-plus-noise ratio values can comprise determiningcapacity data for the starting wideband-based index and the group ofindices of subband information corresponding to the startingwideband-based index based on the signal-to-interference-plus-noiseratio values. Choosing the chosen subband-based index from the group ofindices of subband information based on the first group of link qualitymetric values can comprise selecting as the chosen subband-based index,the subband-based index that in conjunction with the subband-based indexwideband-based index, maximizes capacity data.

Determining the second group of link quality metric values based on thesignal-to-interference-plus-noise ratio values can comprise determiningmutual information values for the indices of wideband information andthe chosen subband-based index of subband information based on thesignal-to-interference-plus-noise ratio values. Selecting the precodingmatrix indicator based on the second group of link quality metric valuescan comprise selecting the precoding matrix indicator based on whichindex of wideband information of the indices of wideband information, inconjunction with the chosen subband-based index, maximizes the mutualinformation values.

Determining the second group of link quality metric values based on thesignal-to-interference-plus-noise ratio values can comprise determiningcapacity data for the indices of wideband information and the chosensubband-based index of subband information based on thesignal-to-interference-plus-noise ratio values. Selecting the precodingmatrix indicator based on the second group of link quality metric valuescan comprise selecting the precoding matrix indicator based on whichindex of wideband information of the indices of wideband information, inconjunction with the chosen subband-based index, maximizes the capacitydata.

FIG. 12 represents example operations of a user equipment device,comprising choosing a starting wideband-based index from indices ofwideband information (operation 1202). Operation 1204 representsdetermining signal-to-interference-plus-noise ratio values for thestarting wideband-based index and a group of indices of subbandinformation corresponding to the initial wideband-based index. Operation1206 represents determining, from the signal-to-interference-plus-noiseratio values, a first group of link quality metric values. Operation1208 represents choosing a subband-based index from the group of indicesof subband information based on the first group of link quality metricvalues, the choosing resulting in a chosen subband-based index.Operation 1210 represents determining a second group of link qualitymetric values based on the indices of wideband information and thechosen subband-based index. Operation 1212 represents reportingparameters corresponding to a precoding matrix indicator based on thesecond group of link quality metric values to a network device.

The first group of link quality metric values can comprise first mutualinformation values, and the second group of link quality metric valuescan comprise second mutual information values. The first group of linkquality metric values can comprise first capacity data and the secondgroup of link quality metric values can comprise second capacity data.

The first group of link quality metric values can comprise first mutualinformation values, the second group of link quality metric values cancomprise second mutual information values, and choosing the chosensubband-based index from the group of indices of subband informationbased on the first group of link quality metric values can comprisedetermining which index of the group of indices of subband informationmaximizes the first mutual information values; reporting the parameterscorresponding to the precoding matrix indicator based on the secondgroup of link quality metric values to a network device can comprisechoosing the precoding matrix indicator by determining which index ofthe indices of wideband information, in conjunction with the chosensubband-based index, maximizes the first mutual information values.

The first group of link quality metric values can comprise firstcapacity data, the second group of link quality metric values cancomprise second capacity data, the choosing the chosen subband-basedindex from the group of indices of subband information based on thefirst group of link quality metric values can comprise determining whichindex of the group of indices of subband information maximizes the firstcapacity data, and reporting the parameters corresponding to theprecoding matrix indicator based on the second group of link qualitymetric values can comprise choosing the precoding matrix indicator bydetermining which index of the indices of wideband information, inconjunction with the chosen subband-based index, maximizes the firstcapacity data.

FIGS. 13 and 14 represent operations, such as in the form of amachine-readable storage medium, comprising executable instructionsthat, when executed by a processor of a user equipment, facilitateperformance of operations. Operation 1302 represents selecting astarting wideband-based index from indices of wideband information.Operation 1304 represents determining signal-to-interference-plus-noiseratio values for the starting wideband-based index and a group ofindices of subband information corresponding to the startingwideband-based index. Operation 1306 represents determining, from thesignal-to-interference-plus-noise ratio values, a first group of linkquality metric values. Operation 1308 represents choosing asubband-based index from the group of indices of subband informationbased on which subband-based index from the group of indices of subbandindices in conjunction with the initial wideband-based index maximizesthe first group of link quality metric values, the choosing thesubband-based index resulting in a chosen subband-based index.

The example continues with operation 1402 of FIG. 14, which representsdetermining a second group of link quality metric values based on theindices of wideband information and the chosen subband-based index.Operation 1404 represents selecting a wideband index from the indices ofwideband information based on which index from the from the indices ofwideband information in conjunction with the selected subband-basedindex satisfies a defined performance criterion for the second group oflink quality metric values, the selecting the wideband index resultingin a selected wideband index. Operation 1406 represents selecting aprecoding matrix indicator based on the selected wideband index and thechosen subband-based index

The first group of link quality metric values can comprise mutualinformation values, and choosing the chosen subband-based index cancomprise determining which subband-based index from the group of indicesof subband indices in conjunction with the starting wideband-based indexmaximizes the mutual information values. The first group of link qualitymetric values can comprise capacity data, and the choosing the chosensubband-based index can comprise determining which subband-based indexfrom the group of indices of subband indices in conjunction with thestarting wideband-based index maximizes the capacity data.

Referring now to FIG. 15, illustrated is an example block diagram of anexample mobile handset 1500 operable to engage in a system architecturethat facilitates wireless communications according to one or moreembodiments described herein. Although a mobile handset is illustratedherein, it will be understood that other devices can be a mobile device,and that the mobile handset is merely illustrated to provide context forthe embodiments of the various embodiments described herein. Thefollowing discussion is intended to provide a brief, general descriptionof an example of a suitable environment in which the various embodimentscan be implemented. While the description includes a general context ofcomputer-executable instructions embodied on a machine-readable storagemedium, those skilled in the art will recognize that the innovation alsocan be implemented in combination with other program modules and/or as acombination of hardware and software.

Generally, applications (e.g., program modules) can include routines,programs, components, data structures, etc., that perform particulartasks or implement particular abstract data types. Moreover, thoseskilled in the art will appreciate that the methods described herein canbe practiced with other system configurations, includingsingle-processor or multiprocessor systems, minicomputers, mainframecomputers, as well as personal computers, hand-held computing devices,microprocessor-based or programmable consumer electronics, and the like,each of which can be operatively coupled to one or more associateddevices

A computing device can typically include a variety of machine-readablemedia. Machine-readable media can be any available media that can beaccessed by the computer and includes both volatile and non-volatilemedia, removable and non-removable media. By way of example and notlimitation, computer-readable media can comprise computer storage mediaand communication media. Computer storage media can include volatileand/or non-volatile media, removable and/or non-removable mediaimplemented in any method or technology for storage of information, suchas computer-readable instructions, data structures, program modules, orother data. Computer storage media can include, but is not limited to,RAM, ROM, EEPROM, flash memory or other memory technology, solid statedrive (SSD) or other solid-state storage technology, Compact Disk ReadOnly Memory (CD ROM), digital video disk (DVD), Blu-ray disk, or otheroptical disk storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to store the desired information and which can be accessed bythe computer. In this regard, the terms “tangible” or “non-transitory”herein as applied to storage, memory or computer-readable media, are tobe understood to exclude only propagating transitory signals per se asmodifiers and do not relinquish rights to all standard storage, memoryor computer-readable media that are not only propagating transitorysignals per se.

Communication media typically embodies computer-readable instructions,data structures, program modules, or other data in a modulated datasignal such as a carrier wave or other transport mechanism, and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media includes wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared and other wireless media. Combinations of the anyof the above should also be included within the scope ofcomputer-readable media

The handset includes a processor 1502 for controlling and processing allonboard operations and functions. A memory 1504 interfaces to theprocessor 1502 for storage of data and one or more applications 1506(e.g., a video player software, user feedback component software, etc.).Other applications can include voice recognition of predetermined voicecommands that facilitate initiation of the user feedback signals. Theapplications 1506 can be stored in the memory 1504 and/or in a firmware1508, and executed by the processor 1502 from either or both the memory1504 or/and the firmware 1508. The firmware 1508 can also store startupcode for execution in initializing the handset 1500. A communicationscomponent 1510 interfaces to the processor 1502 to facilitatewired/wireless communication with external systems, e.g., cellularnetworks, VoIP networks, and so on. Here, the communications component1510 can also include a suitable cellular transceiver 1511 (e.g., a GSMtransceiver) and/or an unlicensed transceiver 1513 (e.g., Wi-Fi, WiMax)for corresponding signal communications. The handset 1500 can be adevice such as a cellular telephone, a PDA with mobile communicationscapabilities, and messaging-centric devices. The communicationscomponent 1510 also facilitates communications reception fromterrestrial radio networks (e.g., broadcast), digital satellite radionetworks, and Internet-based radio services networks

The handset 1500 includes a display 1512 for displaying text, images,video, telephony functions (e.g., a Caller ID function), setupfunctions, and for user input. For example, the display 1512 can also bereferred to as a “screen” that can accommodate the presentation ofmultimedia content (e.g., music metadata, messages, wallpaper, graphics,etc.). The display 1512 can also display videos and can facilitate thegeneration, editing and sharing of video quotes. A serial I/O interface1514 is provided in communication with the processor 1502 to facilitatewired and/or wireless serial communications (e.g., USB, and/or IEEE1594) through a hardwire connection, and other serial input devices(e.g., a keyboard, keypad, and mouse). This supports updating andtroubleshooting the handset 1500, for example. Audio capabilities areprovided with an audio I/O component 1516, which can include a speakerfor the output of audio signals related to, for example, indication thatthe user pressed the proper key or key combination to initiate the userfeedback signal. The audio I/O component 1516 also facilitates the inputof audio signals through a microphone to record data and/or telephonyvoice data, and for inputting voice signals for telephone conversations.

The handset 1500 can include a slot interface 1518 for accommodating aSIC (Subscriber Identity Component) in the form factor of a cardSubscriber Identity Module (SIM) or universal SIM 1520, and interfacingthe SIM card 1520 with the processor 1502. However, it is to beappreciated that the SIM card 1520 can be manufactured into the handset1500, and updated by downloading data and software.

The handset 1500 can process IP data traffic through the communicationscomponent 1510 to accommodate IP traffic from an IP network such as, forexample, the Internet, a corporate intranet, a home network, a personarea network, etc., through an ISP or broadband cable provider. Thus,VoIP traffic can be utilized by the handset 1500 and IP-based multimediacontent can be received in either an encoded or a decoded format.

A video processing component 1522 (e.g., a camera) can be provided fordecoding encoded multimedia content. The video processing component 1522can aid in facilitating the generation, editing, and sharing of videoquotes. The handset 1500 also includes a power source 1524 in the formof batteries and/or an AC power subsystem, which power source 1524 caninterface to an external power system or charging equipment (not shown)by a power I/O component 1526.

The handset 1500 can also include a video component 1530 for processingvideo content received and, for recording and transmitting videocontent. For example, the video component 1530 can facilitate thegeneration, editing and sharing of video quotes. A location trackingcomponent 1532 facilitates geographically locating the handset 1500. Asdescribed hereinabove, this can occur when the user initiates thefeedback signal automatically or manually. A user input component 1534facilitates the user initiating the quality feedback signal. The userinput component 1534 can also facilitate the generation, editing andsharing of video quotes. The user input component 1534 can include suchconventional input device technologies such as a keypad, keyboard,mouse, stylus pen, and/or touch screen, for example.

Referring again to the applications 1506, a hysteresis component 1536facilitates the analysis and processing of hysteresis data, which isutilized to determine when to associate with the access point. Asoftware trigger component 1538 can be provided that facilitatestriggering of the hysteresis component 1536 when the Wi-Fi transceiver1513 detects the beacon of the access point. A SIP client 1540 enablesthe handset 1500 to support SIP protocols and register the subscriberwith the SIP registrar server. The applications 1506 can also include aclient 1542 that provides at least the capability of discovery, play andstore of multimedia content, for example, music.

The handset 1500, as indicated above related to the communicationscomponent 1510, includes an indoor network radio transceiver 1513 (e.g.,Wi-Fi transceiver). This function supports the indoor radio link, suchas IEEE 802.11, for the dual-mode GSM handset 1500. The handset 1500 canaccommodate at least satellite radio services through a handset that cancombine wireless voice and digital radio chipsets into a single handhelddevice.

Referring now to FIG. 16, illustrated is an example block diagram of anexample computer 1600 operable to engage in a system architecture thatfacilitates wireless communications according to one or more embodimentsdescribed herein. The computer 1600 can provide networking andcommunication capabilities between a wired or wireless communicationnetwork and a server (e.g., Microsoft server) and/or communicationdevice. In order to provide additional context for various aspectsthereof, FIG. 16 and the following discussion are intended to provide abrief, general description of a suitable computing environment in whichthe various aspects of the innovation can be implemented to facilitatethe establishment of a transaction between an entity and a third party.While the description above is in the general context ofcomputer-executable instructions that can run on one or more computers,those skilled in the art will recognize that the innovation also can beimplemented in combination with other program modules and/or as acombination of hardware and software.

Generally, program modules include routines, programs, components, datastructures, etc., that perform particular tasks or implement particularabstract data types. Moreover, those skilled in the art will appreciatethat the inventive methods can be practiced with other computer systemconfigurations, including single-processor or multiprocessor computersystems, minicomputers, mainframe computers, as well as personalcomputers, hand-held computing devices, microprocessor-based orprogrammable consumer electronics, and the like, each of which can beoperatively coupled to one or more associated devices.

The illustrated aspects of the innovation can also be practiced indistributed computing environments where certain tasks are performed byremote processing devices that are linked through a communicationsnetwork. In a distributed computing environment, program modules can belocated in both local and remote memory storage devices.

Computing devices typically include a variety of media, which caninclude computer-readable storage media or communications media, whichtwo terms are used herein differently from one another as follows.

Computer-readable storage media can be any available storage media thatcan be accessed by the computer and includes both volatile andnonvolatile media, removable and non-removable media. By way of example,and not limitation, computer-readable storage media can be implementedin connection with any method or technology for storage of informationsuch as computer-readable instructions, program modules, structureddata, or unstructured data. Computer-readable storage media can include,but are not limited to, RAM, ROM, EEPROM, flash memory or other memorytechnology, CD-ROM, digital versatile disk (DVD) or other optical diskstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices, or other tangible and/or non-transitorymedia which can be used to store desired information. Computer-readablestorage media can be accessed by one or more local or remote computingdevices, e.g., via access requests, queries or other data retrievalprotocols, for a variety of operations with respect to the informationstored by the medium.

Communications media can embody computer-readable instructions, datastructures, program modules, or other structured or unstructured data ina data signal such as a modulated data signal, e.g., a carrier wave orother transport mechanism, and includes any information delivery ortransport media. The term “modulated data signal” or signals refers to asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in one or more signals. By way ofexample, and not limitation, communication media include wired media,such as a wired network or direct-wired connection, and wireless mediasuch as acoustic, RF, infrared and other wireless media.

The techniques described herein can be applied to any device or set ofdevices (machines) capable of running programs and processes. It can beunderstood, therefore, that servers including physical and/or virtualmachines, personal computers, laptops, handheld, portable and othercomputing devices and computing objects of all kinds including cellphones, tablet/slate computers, gaming/entertainment consoles and thelike are contemplated for use in connection with various implementationsincluding those exemplified herein. Accordingly, the general purposecomputing mechanism described below with reference to FIG. 16 is but oneexample of a computing device.

In order to provide a context for the various aspects of the disclosedsubject matter, FIG. 16 and the following discussion, are intended toprovide a brief, general description of a suitable environment in whichthe various aspects of the disclosed subject matter can be implemented.While the subject matter has been described above in the general contextof computer-executable instructions of a computer program that runs on acomputer and/or computers, those skilled in the art will recognize thatthe disclosed subject matter also can be implemented in combination withother program modules. Generally, program modules include routines,programs, components, data structures, etc. that perform particulartasks and/or implement particular abstract data types.

In the subject specification, terms such as “store,” “storage,” “datastore,” data storage,” “database,” and substantially any otherinformation storage component relevant to operation and functionality ofa component, refer to “memory components,” or entities embodied in a“memory” or components comprising the memory. It will be appreciatedthat the memory components described herein can be either volatilememory or nonvolatile memory, or can include both volatile andnonvolatile memory, by way of illustration, and not limitation, volatilememory 1620 (see below), non-volatile memory 1622 (see below), diskstorage 1624 (see below), and memory storage 1646 (see below). Further,nonvolatile memory can be included in read only memory (ROM),programmable ROM (PROM), electrically programmable ROM (EPROM),electrically erasable ROM (EEPROM), or flash memory. Volatile memory caninclude random access memory (RAM), which acts as external cache memory.By way of illustration and not limitation, RAM is available in manyforms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronousDRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM(ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM).Additionally, the disclosed memory components of systems or methodsherein are intended to comprise, without being limited to comprising,these and any other suitable types of memory.

Moreover, it will be noted that the disclosed subject matter can bepracticed with other computer system configurations, includingsingle-processor or multiprocessor computer systems, mini-computingdevices, mainframe computers, as well as personal computers, hand-heldcomputing devices (e.g., PDA, phone, watch, tablet computers, netbookcomputers, . . . ), microprocessor-based or programmable consumer orindustrial electronics, and the like. The illustrated aspects can alsobe practiced in distributed computing environments where tasks areperformed by remote processing devices that are linked through acommunications network; however, some if not all aspects of the subjectdisclosure can be practiced on stand-alone computers. In a distributedcomputing environment, program modules can be located in both local andremote memory storage devices.

FIG. 16 illustrates a block diagram of a computing system 1600 operableto execute the disclosed systems and methods in accordance with anembodiment. Computer 1612, which can be, for example, part of thehardware of system 1620, includes a processing unit 1614, a systemmemory 1616, and a system bus 1618. System bus 1618 couples systemcomponents including, but not limited to, system memory 1616 toprocessing unit 1614. Processing unit 1614 can be any of variousavailable processors. Dual microprocessors and other multiprocessorarchitectures also can be employed as processing unit 1614.

System bus 1618 can be any of several types of bus structure(s)including a memory bus or a memory controller, a peripheral bus or anexternal bus, and/or a local bus using any variety of available busarchitectures including, but not limited to, Industrial StandardArchitecture (ISA), Micro-Channel Architecture (MSA), Extended ISA(EISA), Intelligent Drive Electronics, VESA Local Bus (VLB), PeripheralComponent Interconnect (PCI), Card Bus, Universal Serial Bus (USB),Advanced Graphics Port (AGP), Personal Computer Memory CardInternational Association bus (PCMCIA), Firewire (IEEE 1694), and SmallComputer Systems Interface (SCSI).

System memory 1616 can include volatile memory 1620 and nonvolatilememory 1622. A basic input/output system (BIOS), containing routines totransfer information between elements within computer 1612, such asduring start-up, can be stored in nonvolatile memory 1622. By way ofillustration, and not limitation, nonvolatile memory 1622 can includeROM, PROM, EPROM, EEPROM, or flash memory. Volatile memory 1620 includesRAM, which acts as external cache memory. By way of illustration and notlimitation, RAM is available in many forms such as SRAM, dynamic RAM(DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM),enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), Rambus direct RAM(RDRAM), direct Rambus dynamic RAM (DRDRAM), and Rambus dynamic RAM(RDRAM).

Computer 1612 can also include removable/non-removable,volatile/non-volatile computer storage media. FIG. 16 illustrates, forexample, disk storage 1624. Disk storage 1624 includes, but is notlimited to, devices like a magnetic disk drive, floppy disk drive, tapedrive, flash memory card, or memory stick. In addition, disk storage1624 can include storage media separately or in combination with otherstorage media including, but not limited to, an optical disk drive suchas a compact disk ROM device (CD-ROM), CD recordable drive (CD-R Drive),CD rewritable drive (CD-RW Drive) or a digital versatile disk ROM drive(DVD-ROM). To facilitate connection of the disk storage devices 1624 tosystem bus 1618, a removable or non-removable interface is typicallyused, such as interface 1626.

Computing devices typically include a variety of media, which caninclude computer-readable storage media or communications media, whichtwo terms are used herein differently from one another as follows.

Computer-readable storage media can be any available storage media thatcan be accessed by the computer and includes both volatile andnonvolatile media, removable and non-removable media. By way of example,and not limitation, computer-readable storage media can be implementedin connection with any method or technology for storage of informationsuch as computer-readable instructions, program modules, structureddata, or unstructured data. Computer-readable storage media can include,but are not limited to, random access memory (RAM), read only memory(ROM), electrically erasable programmable read only memory (EEPROM),flash memory or other memory technology, solid state drive (SSD) orother solid-state storage technology, compact disk read only memory (CDROM), digital versatile disk (DVD), Blu-ray disc or other optical diskstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices or other tangible and/or non-transitorymedia which can be used to store desired information. In this regard,the terms “tangible” or “non-transitory”herein as applied to storage,memory or computer-readable media, are to be understood to exclude onlypropagating transitory signals per se as modifiers and do not relinquishrights to all standard storage, memory or computer-readable media thatare not only propagating transitory signals per se. In an aspect,tangible media can include non-transitory media wherein the term“non-transitory” herein as may be applied to storage, memory orcomputer-readable media, is to be understood to exclude only propagatingtransitory signals per se as a modifier and does not relinquish coverageof all standard storage, memory or computer-readable media that are notonly propagating transitory signals per se. For the avoidance of doubt,the term “computer-readable storage device” is used and defined hereinto exclude transitory media. Computer-readable storage media can beaccessed by one or more local or remote computing devices, e.g., viaaccess requests, queries or other data retrieval protocols, for avariety of operations with respect to the information stored by themedium.

Communications media typically embody computer-readable instructions,data structures, program modules or other structured or unstructureddata in a data signal such as a modulated data signal, e.g., a carrierwave or other transport mechanism, and includes any information deliveryor transport media. The term “modulated data signal” or signals refersto a signal that has one or more of its characteristics set or changedin such a manner as to encode information in one or more signals. By wayof example, and not limitation, communication media include wired media,such as a wired network or direct-wired connection, and wireless mediasuch as acoustic, RF, infrared and other wireless media.

It can be noted that FIG. 16 describes software that acts as anintermediary between users and computer resources described in suitableoperating environment 1600. Such software includes an operating system1628. Operating system 1628, which can be stored on disk storage 1624,acts to control and allocate resources of computer system 1612. Systemapplications 1630 take advantage of the management of resources byoperating system 1628 through program modules 1632 and program data 1634stored either in system memory 1616 or on disk storage 1624. It is to benoted that the disclosed subject matter can be implemented with variousoperating systems or combinations of operating systems.

A user can enter commands or information into computer 1612 throughinput device(s) 1636. As an example, a mobile device and/or portabledevice can include a user interface embodied in a touch sensitivedisplay panel allowing a user to interact with computer 1612. Inputdevices 1636 include, but are not limited to, a pointing device such asa mouse, trackball, stylus, touch pad, keyboard, microphone, joystick,game pad, satellite dish, scanner, TV tuner card, digital camera,digital video camera, web camera, cell phone, smartphone, tabletcomputer, etc. These and other input devices connect to processing unit1614 through system bus 1618 by way of interface port(s) 1638. Interfaceport(s) 1638 include, for example, a serial port, a parallel port, agame port, a universal serial bus (USB), an infrared port, a Bluetoothport, an IP port, or a logical port associated with a wireless service,etc. Output device(s) 1640 and a move use some of the same type of portsas input device(s) 1636.

Thus, for example, a USB port can be used to provide input to computer1612 and to output information from computer 1612 to an output device1640. Output adapter 1642 is provided to illustrate that there are someoutput devices 1640 like monitors, speakers, and printers, among otheroutput devices 1640, which use special adapters. Output adapters 1642include, by way of illustration and not limitation, video and soundcards that provide means of connection between output device 1640 andsystem bus 1618. It should be noted that other devices and/or systems ofdevices provide both input and output capabilities such as remotecomputer(s) 1644.

Computer 1612 can operate in a networked environment using logicalconnections to one or more remote computers, such as remote computer(s)1644. Remote computer(s) 1644 can be a personal computer, a server, arouter, a network PC, cloud storage, cloud service, a workstation, amicroprocessor based appliance, a peer device, or other common networknode and the like, and typically includes many or all of the elementsdescribed relative to computer 1612.

For purposes of brevity, only a memory storage device 1646 isillustrated with remote computer(s) 1644. Remote computer(s) 1644 islogically connected to computer 1612 through a network interface 1648and then physically connected by way of communication connection 1650.Network interface 1648 encompasses wire and/or wireless communicationnetworks such as local-area networks (LAN) and wide-area networks (WAN).LAN technologies include Fiber Distributed Data Interface (FDDI), CopperDistributed Data Interface (CDDI), Ethernet, Token Ring and the like.WAN technologies include, but are not limited to, point-to-point links,circuit-switching networks like Integrated Services Digital Networks(ISDN) and variations thereon, packet switching networks, and DigitalSubscriber Lines (DSL). As noted below, wireless technologies may beused in addition to or in place of the foregoing.

Communication connection(s) 1650 refer(s) to hardware/software employedto connect network interface 1648 to bus 1618. While communicationconnection 1650 is shown for illustrative clarity inside computer 1612,it can also be external to computer 1612. The hardware/software forconnection to network interface 1648 can include, for example, internaland external technologies such as modems, including regular telephonegrade modems, cable modems and DSL modems, ISDN adapters, and Ethernetcards.

The above description of illustrated embodiments of the subjectdisclosure, including what is described in the Abstract, is not intendedto be exhaustive or to limit the disclosed embodiments to the preciseforms disclosed. While specific embodiments and examples are describedherein for illustrative purposes, various modifications are possiblethat are considered within the scope of such embodiments and examples,as those skilled in the relevant art can recognize.

In this regard, while the disclosed subject matter has been described inconnection with various embodiments and corresponding Figures, whereapplicable, it is to be understood that other similar embodiments can beused or modifications and additions can be made to the describedembodiments for performing the same, similar, alternative, or substitutefunction of the disclosed subject matter without deviating therefrom.Therefore, the disclosed subject matter should not be limited to anysingle embodiment described herein, but rather should be construed inbreadth and scope in accordance with the appended claims below.

As it employed in the subject specification, the term “processor” canrefer to substantially any computing processing unit or devicecomprising, but not limited to comprising, single-core processors;single-processors with software multithread execution capability;multi-core processors; multi-core processors with software multithreadexecution capability; multi-core processors with hardware multithreadtechnology; parallel platforms; and parallel platforms with distributedshared memory. Additionally, a processor can refer to an integratedcircuit, an application specific integrated circuit (ASIC), a digitalsignal processor (DSP), a field programmable gate array (FPGA), aprogrammable logic controller (PLC), a complex programmable logic device(CPLD), a discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. Processors can exploit nano-scale architectures suchas, but not limited to, molecular and quantum-dot based transistors,switches and gates, in order to optimize space usage or enhanceperformance of user equipment. A processor may also be implemented as acombination of computing processing units.

In the subject specification, terms such as “store,” “storage,” “datastore,” data storage,” “database,” and substantially any otherinformation storage component relevant to operation and functionality ofa component, refer to “memory components,” or entities embodied in a“memory” or components comprising the memory. It will be appreciatedthat the memory components described herein can be either volatilememory or nonvolatile memory, or can include both volatile andnonvolatile memory.

As used in this application, the terms “component,” “system,”“platform,” “layer,” “selector,” “interface,” and the like are intendedto refer to a computer-related entity or an entity related to anoperational apparatus with one or more specific functionalities, whereinthe entity can be either hardware, a combination of hardware andsoftware, software, or software in execution. As an example, a componentmay be, but is not limited to being, a process running on a processor, aprocessor, an object, an executable, a thread of execution, a program,and/or a computer. By way of illustration and not limitation, both anapplication running on a server and the server can be a component. Oneor more components may reside within a process and/or thread ofexecution and a component may be localized on one computer and/ordistributed between two or more computers. In addition, these componentscan execute from various computer readable media, device readablestorage devices, or machine readable media having various datastructures stored thereon. The components may communicate via localand/or remote processes such as in accordance with a signal having oneor more data packets (e.g., data from one component interacting withanother component in a local system, distributed system, and/or across anetwork such as the Internet with other systems via the signal). Asanother example, a component can be an apparatus with specificfunctionality provided by mechanical parts operated by electric orelectronic circuitry, which is operated by a software or firmwareapplication executed by a processor, wherein the processor can beinternal or external to the apparatus and executes at least a part ofthe software or firmware application. As yet another example, acomponent can be an apparatus that provides specific functionalitythrough electronic components without mechanical parts, the electroniccomponents can include a processor therein to execute software orfirmware that confers at least in part the functionality of theelectronic components.

In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom context, “X employs A or B” is intended to mean any of the naturalinclusive permutations. That is, if X employs A; X employs B; or Xemploys both A and B, then “X employs A or B” is satisfied under any ofthe foregoing instances. Moreover, articles “a” and “an” as used in thesubject specification and annexed drawings should generally be construedto mean “one or more” unless specified otherwise or clear from contextto be directed to a singular form.

Moreover, terms like “user equipment (UE),” “mobile station,” “mobile,”subscriber station,” “subscriber equipment,” “access terminal,”“terminal,” “handset,” and similar terminology, refer to a wirelessdevice utilized by a subscriber or user of a wireless communicationservice to receive or convey data, control, voice, video, sound, gaming,or substantially any data-stream or signaling-stream. The foregoingterms are utilized interchangeably in the subject specification andrelated drawings. Likewise, the terms “access point (AP),” “basestation,” “NodeB,” “evolved Node B (eNodeB),” “home Node B (HNB),” “homeaccess point (HAP),” “cell device,” “sector,” “cell,” and the like, areutilized interchangeably in the subject application, and refer to awireless network component or appliance that serves and receives data,control, voice, video, sound, gaming, or substantially any data-streamor signaling-stream to and from a set of subscriber stations or providerenabled devices. Data and signaling streams can include packetized orframe-based flows.

Additionally, the terms “core-network”, “core”, “core carrier network”,“carrier-side”, or similar terms can refer to components of atelecommunications network that typically provides some or all ofaggregation, authentication, call control and switching, charging,service invocation, or gateways. Aggregation can refer to the highestlevel of aggregation in a service provider network wherein the nextlevel in the hierarchy under the core nodes is the distribution networksand then the edge networks. UEs do not normally connect directly to thecore networks of a large service provider but can be routed to the coreby way of a switch or radio area network. Authentication can refer todeterminations regarding whether the user requesting a service from thetelecom network is authorized to do so within this network or not. Callcontrol and switching can refer determinations related to the futurecourse of a call stream across carrier equipment based on the callsignal processing. Charging can be related to the collation andprocessing of charging data generated by various network nodes. Twocommon types of charging mechanisms found in present day networks can beprepaid charging and postpaid charging. Service invocation can occurbased on some explicit action (e.g. call transfer) or implicitly (e.g.,call waiting). It is to be noted that service “execution” may or may notbe a core network functionality as third party network/nodes may takepart in actual service execution. A gateway can be present in the corenetwork to access other networks. Gateway functionality can be dependenton the type of the interface with another network.

Furthermore, the terms “user,” “subscriber,” “customer,” “consumer,”“prosumer,” “agent,” and the like are employed interchangeablythroughout the subject specification, unless context warrants particulardistinction(s) among the terms. It should be appreciated that such termscan refer to human entities or automated components (e.g., supportedthrough artificial intelligence, as through a capacity to makeinferences based on complex mathematical formalisms), that can providesimulated vision, sound recognition and so forth.

Aspects, features, or advantages of the subject matter can be exploitedin substantially any, or any, wired, broadcast, wirelesstelecommunication, radio technology or network, or combinations thereof.Non-limiting examples of such technologies or networks include Geocasttechnology; broadcast technologies (e.g., sub-Hz, ELF, VLF, LF, MF, HF,VHF, UHF, SHF, THz broadcasts, etc.); Ethernet; X.25; powerline-typenetworking (e.g., PowerLine AV Ethernet, etc.); femto-cell technology;Wi-Fi; Worldwide Interoperability for Microwave Access (WiMAX); EnhancedGeneral Packet Radio Service (Enhanced GPRS); Third GenerationPartnership Project (3GPP or 3G) Long Term Evolution (LTE); 3GPPUniversal Mobile Telecommunications System (UMTS) or 3GPP UMTS; ThirdGeneration Partnership Project 2 (3GPP2) Ultra Mobile Broadband (UMB);High Speed Packet Access (HSPA); High Speed Downlink Packet Access(HSDPA); High Speed Uplink Packet Access (HSUPA); GSM Enhanced DataRates for GSM Evolution (EDGE) Radio Access Network (RAN) or GERAN; UMTSTerrestrial Radio Access Network (UTRAN); or LTE Advanced.

What has been described above includes examples of systems and methodsillustrative of the disclosed subject matter. It is, of course, notpossible to describe every combination of components or methods herein.One of ordinary skill in the art may recognize that many furthercombinations and permutations of the disclosure are possible.Furthermore, to the extent that the terms “includes,” “has,”“possesses,” and the like are used in the detailed description, claims,appendices and drawings such terms are intended to be inclusive in amanner similar to the term “comprising” as “comprising” is interpretedwhen employed as a transitional word in a claim.

While the various embodiments are susceptible to various modificationsand alternative constructions, certain illustrated implementationsthereof are shown in the drawings and have been described above indetail. It should be understood, however, that there is no intention tolimit the various embodiments to the specific forms disclosed, but onthe contrary, the intention is to cover all modifications, alternativeconstructions, and equivalents falling within the spirit and scope ofthe various embodiments.

In addition to the various implementations described herein, it is to beunderstood that other similar implementations can be used ormodifications and additions can be made to the describedimplementation(s) for performing the same or equivalent function of thecorresponding implementation(s) without deviating therefrom. Stillfurther, multiple processing chips or multiple devices can share theperformance of one or more functions described herein, and similarly,storage can be effected across a plurality of devices. Accordingly, theinvention is not to be limited to any single implementation, but ratheris to be construed in breadth, spirit and scope in accordance with theappended claims.

What is claimed is:
 1. A method, comprising: selecting, by a userequipment comprising a processor, a starting wideband-based index fromindices of wideband information; determining, by the user equipment,signal-to-interference-plus-noise ratio values for the startingwideband-based index and a group of indices of subband informationcorresponding to the starting wideband-based index; determining, by theuser equipment based on the signal-to-interference-plus-noise ratiovalues, a first group of link quality metric values; choosing, by theuser equipment, a chosen subband-based index from the group of indicesof subband information based on the first group of link quality metricvalues; determining, by the user equipment, a second group of linkquality metric values based on the indices of wideband information andthe chosen subband-based index; and selecting, by the user equipment, aprecoding matrix indicator based on the second group of link qualitymetric values.
 2. The method of claim 1, wherein the selecting theprecoding matrix indicator comprises searching a codebook based on aselected wideband index and the chosen subband-based index.
 3. Themethod of claim 1, further comprising estimating, by the user equipment,a channel, wherein the determining the signal-to-interference-plus-noiseratio values comprises determining the signal-to-interference-plus-noiseratio values based on the channel.
 4. The method of claim 1, furthercomprising reporting, by the user equipment, parameter valuescorresponding to the precoding matrix indicator to a network device. 5.The method of claim 1, wherein the determining the first group of linkquality metric values based on the signal-to-interference-plus-noiseratio values comprises determining mutual information values for thestarting wideband-based index and the group of indices of subbandinformation corresponding to the initial wideband-based index based onthe signal-to-interference-plus-noise ratio values.
 6. The method ofclaim 5, wherein the choosing the chosen subband-based index from thegroup of indices of subband information based on the first group of linkquality metric values comprises selecting the subband-based index, whichin conjunction with the starting wideband-based index, maximizes mutualinformation values based on the signal-to-interference-plus-noise ratiovalues.
 7. The method of claim 1, wherein the determining the firstgroup of link quality metric values based on thesignal-to-interference-plus-noise ratio values comprises determiningcapacity data for the starting wideband-based index and the group ofindices of subband information corresponding to the startingwideband-based index based on the signal-to-interference-plus-noiseratio values.
 8. The method of claim 7, wherein the choosing the chosensubband-based index from the group of indices of subband informationbased on the first group of link quality metric values comprisesselecting as the chosen subband-based index, the subband-based indexthat in conjunction with the subband-based index wideband-based index,maximizes capacity data.
 9. The method of claim 1, wherein thedetermining the second group of link quality metric values based on thesignal-to-interference-plus-noise ratio values comprises determiningmutual information values for the indices of wideband information andthe chosen subband-based index of subband information based on thesignal-to-interference-plus-noise ratio values.
 10. The method of claim9, wherein the selecting the precoding matrix indicator based on thesecond group of link quality metric values comprises selecting theprecoding matrix indicator based on which index of wideband informationof the indices of wideband information, in conjunction with the chosensubband-based index, maximizes the mutual information values.
 11. Themethod of claim 1, wherein the determining the second group of linkquality metric values based on the signal-to-interference-plus-noiseratio values comprises determining capacity data for the indices ofwideband information and the chosen subband-based index of subbandinformation based on the signal-to-interference-plus-noise ratio values.12. The method of claim 11, wherein the selecting the precoding matrixindicator based on the second group of link quality metric valuescomprises selecting the precoding matrix indicator based on which indexof wideband information of the indices of wideband information, inconjunction with the chosen subband-based index, maximizes the capacitydata.
 13. A user equipment device, comprising: a processor; and a memorythat stores executable instructions that, when executed by theprocessor, facilitate performance of operations, the operationscomprising: choosing a starting wideband-based index from indices ofwideband information; determining signal-to-interference-plus-noiseratio values for the starting wideband-based index and a group ofindices of subband information corresponding to the initialwideband-based index; determining, from thesignal-to-interference-plus-noise ratio values, a first group of linkquality metric values; choosing a subband-based index from the group ofindices of subband information based on the first group of link qualitymetric values, the choosing resulting in a chosen subband-based index;determining a second group of link quality metric values based on theindices of wideband information and the chosen subband-based index; andreporting parameters corresponding to a precoding matrix indicator basedon the second group of link quality metric values to a network device.14. The user equipment device of claim 13, wherein the first group oflink quality metric values comprise first mutual information values, andwherein the second group of link quality metric values comprise secondmutual information values.
 15. The user equipment device of claim 13,wherein the first group of link quality metric values comprise firstcapacity data and wherein the second group of link quality metric valuescomprise second capacity data.
 16. The user equipment device of claim13, wherein the first group of link quality metric values comprise firstmutual information values, wherein the second group of link qualitymetric values comprise second mutual information values, wherein thechoosing the chosen subband-based index from the group of indices ofsubband information based on the first group of link quality metricvalues comprises determining which index of the group of indices ofsubband information maximizes the first mutual information values, andwherein the reporting the parameters corresponding to the precodingmatrix indicator based on the second group of link quality metric valuesto a network device comprises choosing the precoding matrix indicator bydetermining which index of the indices of wideband information, inconjunction with the chosen subband-based index, maximizes the firstmutual information values.
 17. The user equipment device of claim 13,wherein the first group of link quality metric values comprises firstcapacity data, wherein the second group of link quality metric valuescomprises second capacity data, wherein the choosing the chosensubband-based index from the group of indices of subband informationbased on the first group of link quality metric values comprisesdetermining which index of the group of indices of subband informationmaximizes the first capacity data, and wherein the reporting theparameters corresponding to the precoding matrix indicator based on thesecond group of link quality metric values comprises choosing theprecoding matrix indicator by determining which index of the indices ofwideband information, in conjunction with the chosen subband-basedindex, maximizes the first capacity data.
 18. A machine-readable storagemedium, comprising executable instructions that, when executed by aprocessor of a radio user equipment, facilitate performance ofoperations, the operations comprising: selecting a startingwideband-based index from indices of wideband information; determiningsignal-to-interference-plus-noise ratio values for the startingwideband-based index and a group of indices of subband informationcorresponding to the starting wideband-based index; determining, fromthe signal-to-interference-plus-noise ratio values, a first group oflink quality metric values; choosing a subband-based index from thegroup of indices of subband information based on which subband-basedindex from the group of indices of subband indices in conjunction withthe initial wideband-based index maximizes the first group of linkquality metric values, the choosing the subband-based index resulting ina chosen subband-based index; determining a second group of link qualitymetric values based on the indices of wideband information and thechosen subband-based index; selecting a wideband index from the indicesof wideband information based on which index from the from the indicesof wideband information in conjunction with the selected subband-basedindex satisfies a defined performance criterion for the second group oflink quality metric values, the selecting the wideband index resultingin a selected wideband index; and selecting a precoding matrix indicatorbased on the selected wideband index and the chosen subband-based index.19. The machine-readable storage medium of claim 18, wherein the firstgroup of link quality metric values comprises mutual information values,and wherein the choosing the chosen subband-based index comprisesdetermining which subband-based index from the group of indices ofsubband indices in conjunction with the starting wideband-based indexmaximizes the mutual information values.
 20. The machine-readablestorage medium of claim 18, wherein the first group of link qualitymetric values comprises capacity data, and wherein the choosing thechosen subband-based index comprises determining which subband-basedindex from the group of indices of subband indices in conjunction withthe starting wideband-based index maximizes the capacity data.